JP2005244039A - Printed wiring board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed wiring board for which peeling is not generated in a conductor circuit. <P>SOLUTION: In the printed wiring board, the conductor circuit is composed of two or more kinds of metal layer parts, and at least the width of a second metal part on an inner layer side is larger than the width of a first metal part on an outer layer side. In a method of manufacturing the printed wiring board by a transfer method, after forming the two or more kinds of metal layer parts by a plating processing on a metal carrier, the metal parts are etched such that at least the width of the first metal part on the outer layer side of the metal layer parts becomes smaller than the width of the second metal part on the inner layer side, the conductor circuit is formed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a printed wiring board in which a conductor circuit is formed flat on an outer layer of a printed wiring board with respect to an insulating substrate, and the adhesion of the conductor circuit is improved, and a manufacturing method thereof.

  Conventionally, a transfer method is known as a method of flattening the outermost conductor circuit of a printed wiring board (see, for example, Patent Document 1). This method generally involves forming a conductor circuit by depositing metal plating on one side of a stainless steel plate, then laminating an insulating base material, and then peeling off the stainless steel metal carrier to form the outermost layer of the printed wiring board. The conductor circuit is formed flat.

  However, in the case of such a transfer method, after forming a conductor circuit and laminating it on the insulating layer, there is a problem that when the stainless steel as the metal carrier is peeled off, a load is applied to the insulating layer and the conductor circuit is peeled off. .

  In particular, stainless steel, which is a metal carrier, generally has a thickness of about 0.8 mm and is rigid. Therefore, when peeling off, it cannot be peeled off unless the insulating layer is bent. At this time, the conductor circuit is easily peeled off. It was real.

In addition, recent mobile products such as electronic dictionaries and electronic books are also required to have a thin printed wiring board. However, since the board is thin, flexibility is also required. There was also a problem that the conductor circuit was peeled off.
Japanese Patent Laid-Open No. 11-8451

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide a printed wiring board in which peeling does not occur in a conductor circuit.

  In the printed wiring board according to the present invention, the conductor circuit formed on the metal carrier includes two or more types of metal layer portions, and at least the second metal portion on the inner layer side is larger than the width of the first metal portion on the outer layer side. The above objective was achieved by taking the structure.

  Since such a structure, that is, the second metal portion is larger than the width of the first metal portion, the shape of the second metal portion becomes an anchor shape. As a result, the adhesion with the insulating layer is improved and the conductor circuit is not peeled off.

  The present invention also relates to a printed wiring board manufacturing method in which a metal circuit is deposited on a metal carrier to form a conductor circuit, and then an insulating layer is laminated, and then the metal carrier is peeled off to form a circuit pattern of the outermost layer. 2, after forming two or more types of metal layer portions on the metal carrier by plating, the width of at least the first metal portion on the outer layer side of the metal layer portion is larger than the width of the second metal portion on the inner layer side. The object was achieved by etching the metal layer part to form a conductor circuit so as to be smaller.

  By using such a manufacturing method, that is, using two or more kinds of metals as a conductor circuit and etching the two or more kinds of metals with different widths, an anchor-shaped conductor circuit is formed. A printed wiring board with improved adhesion can be obtained.

  According to the present invention, since the conductor circuit and the insulating layer are in close contact with each other, it is possible to obtain a printed wiring board in which no peeling occurs in the conductor circuit.

  FIG. 1 is a schematic cross-sectional explanatory view of a printed wiring board of the present invention. The printed wiring board of the present invention will be described below with reference to FIG.

  Reference numeral 7 denotes a printed wiring board in which the conductor circuit 3 is embedded flat. The conductor circuit 3 includes a first metal portion 3a on the outer layer side and a second metal portion 3b on the inner layer side, and the first metal portion 3a and the second metal portion 3b are made of different kinds of metals. Specific examples of such metals include copper, aluminum, silver, gold, nickel, solder (Sn—Pb, Sn—Ag—Cu, Sn—Ag, Sn—Ag—Bi, Sn—Zn) and the like. Two or more of these are appropriately selected and used.

  The width of the second metal portion 3b on the inner layer side is larger than the width of the first metal portion 3a on the outer layer side, and the width of the first metal portion 3a is gradually smaller from the outer layer side toward the inner layer side. It has become.

  FIG. 2 is a schematic cross-sectional process explanatory diagram showing a method for producing a printed wiring board of the present invention. Hereinafter, a method for producing a printed wiring board according to the present invention will be described with reference to FIG.

  FIG. 2 (a) shows a metal carrier 1, and examples of the material include stainless steel, aluminum, copper, nickel, and the like. These include single material or composite material, multilayer plate, multilayer foil, and the like. used. A thin copper plating 2 is applied to one side of the metal carrier 1 by electroless electrolysis. Incidentally, if a copper carrier with an ultrathin copper foil is used in advance, the electroless thin copper plating treatment is not necessary, which can simplify the manufacturing process and is preferable. In addition, as a copper carrier, a general copper plate or copper foil can be used, and those having a thickness of several tens of μm are easy to peel off, and are particularly suitable for thin printed wiring boards.

  Next, a conductor circuit is formed on the metal carrier 1, and a subtractive method or an additive method is employed as a method of forming the conductor circuit. In FIG. 2, (b) to (f) indicate the subtractive method, and (g) to (j) indicate the semi-additive method.

  In the conductor circuit formation by the subtractive method, first, as shown in FIG. 2B, the first metal part 3a and the second metal part 3b for the conductor circuit are deposited on one side of the metal carrier 1 by plating. The specific metal types of the first metal part 3a and the second metal part 3b are, for example, copper, aluminum, silver, gold, nickel, solder (Sn—Pb, Sn—Ag—Cu, Sn—Ag) as described above. , Sn-Ag-Bi, Sn-Zn), and the like, which are appropriately selected and used.

  Next, as shown in FIG. 2 (c), a photoresist pattern 4 is formed on the second metal portion 3b, and then the second metal portion 3b exposed from the opening is etched as shown in FIG. 2 (d). Then, circuit formation is performed. The etching solution used at this time dissolves the second metal part 3b and does not dissolve the first metal part 3a, or a chemical solution capable of selective etching, or dissolves the second metal part 3b but dissolves the first metal part. For 3a, a chemical solution that makes a difference in etching rate that only slightly dissolves is selected.

  Next, after removing the photoresist 4 as shown in FIG. 2 (e), the first metal part 3a is etched as shown in FIG. 2 (f) to form the conductor circuit 3. As the etching solution used at this time, a chemical solution that can etch away the first metal portion 3a but cannot etch the second metal portion 3b is selected. At this time, the etching is performed so that the width of the first metal portion 3a is smaller than the width of the second metal portion 3b. In particular, as shown in FIG. 1, the width of the first metal portion 3a is gradually reduced from the outer layer side toward the inner layer side, and the second metal portion 3b is wider than the first metal portion 3a immediately above. It is desirable to form the conductor circuit 3 because the conductor circuit 3 has a more anchor shape and the adhesion to the insulating layer 6 can be made stronger.

  On the other hand, in the formation of a conductor circuit by the semi-additive method, a thin copper plating 2 is deposited on one side of the metal carrier 1 by electroless method (FIG. 2A), and then a photoresist pattern as shown in FIG. Then, as shown in FIG. 2 (h), the first metal portion 3a and the second metal portion 3b are deposited in the opening by electrolytic plating. As the specific metal of the first metal part 3a and the second metal part 3b used at this time, the same metal as the subtractive is used.

  Next, as shown in FIG. 2 (i), after the photoresist 5 is peeled off, the conductor circuit 3 is formed by etching as shown in FIG. 2 (j). As the etching solution used at this time, a chemical solution that can be etched away from the first metal portion 3a but cannot be etched from the second metal portion 3b is used. Moreover, when it is 2, it etches so that the width | variety of the 1st metal part 3a may become smaller than the width | variety of the 2nd metal part 3b. In particular, as shown in FIG. 1, the width of the first metal portion 3a is gradually reduced from the outer layer side toward the inner layer side, and the second metal portion 3b is wider than the first metal portion 3a immediately above. It is desirable to form the conductor circuit 3 because the conductor circuit 3 has an anchor shape and can be more firmly adhered to the insulating layer 6.

  After the conductor circuit 3 is formed, the same process is performed as follows regardless of the subtractive method or the additive method.

That is, as shown in FIGS. 2 (k) and 2 (l), the insulating layer 6 is formed on the metal carrier 1 to which the conductor circuit 3 is applied. As a method for forming the insulating layer, if the insulating substrate is in the form of a sheet, it is a method of pressure bonding such as a laminating press or a laminator, and if it is a liquid, it is a spin coater, blade coater, roll coater, bar coder. Application by die coater or screen printing is also possible. In particular, when the conductor circuit 3 is fine, the insulating base material is sheet-like, and the formation of the insulating layer by a vacuum press or a vacuum laminator can be favorably manufactured without voids, which is desirable.
The thermosetting resin sheet-like insulating base material suitably used here is thermosetting to a single resin sheet, glass fiber, aramid fiber, carbon fiber, glass nonwoven fabric, aramid nonwoven fabric, carbon nonwoven fabric, etc. Examples thereof include a prepreg impregnated with a resin or a thermoplastic resin. Examples of the thermosetting resin include epoxy, polyimide, and BT resin. Examples of the thermoplastic resin include polycarbonate, polyether sulfide, polyethylene terephthalate, polyether imide, polyimide, polyamide, and liquid crystal polymer. In particular, a liquid crystal polymer is preferably used from the viewpoint of excellent electrical characteristics such as low dielectric loss, processability, and adhesion to metal.

  Next, as shown in FIG. 2 (m), the metal carrier 1 is peeled off from the insulating substrate. At this time, the insulating substrate is peeled off without applying stress. Moreover, you may remove the metal carrier 1 with a chemical | medical solution.

  Next, as shown in FIG. 2 (n), the electroless copper plating 2 is removed by etching. Etching solutions used for this include aqueous solutions of cupric chloride, ferric chloride, persulfates, hydrogen peroxide / sulfuric acid, alkaline etchant, etc., but the conductor circuit 3 is removed at the same time as the electroless copper plating 2 is removed. In the case of an etching solution that also dissolves, it is necessary to adjust the processing time and the like. If possible, it is preferable to select an etching solution that dissolves the electroless copper plating 2 but does not dissolve the conductor circuit 3. Thereby, the printed wiring board 7 is obtained.

  The printed wiring board of the present invention is suitably used for wiring boards for electronic equipment, interposers for IC packages, and the like. It is also possible to insert a resistance element or a capacitance element in the conductor circuit as appropriate.

  Hereinafter, the present invention will be further described with reference to Examples and Comparative Examples. In addition, the code | symbol of an Example quoted the code | symbol of FIG. 2, and the code | symbol of the comparative example quoted the code | symbol of FIG. 3, respectively.

Example 1
1 μm of electroless copper plating 2 was deposited on one side of a 0.8 mm thick stainless steel plate 1 by electroless copper plating. Then, 10 μm of the first metal part 3a made of nickel plating was deposited by electrolytic plating, and then 5 μm of the second metal part 3b made of copper plating was deposited. Next, the photoresist 4 was adhered by a laminator and left at room temperature for 5 minutes, and then the photoresist 4 was exposed through a photomask. The test photomask pattern was a line (L) / space (S) = 10 μm / 10 μm, 15 μm / 15 μm, 20 μm / 20 μm, and thereafter 100 μm / 100 μm in increments of 10 μm, and was a negative type. Photoresist 4 was developed, and a resist layer was formed on a portion requiring a plating thickness. Next, only the copper plating as the second metal part 3b is removed with an etching solution (alkali etching solution (Mertex Co., Ltd. Ace Process)), and after the resist is peeled off with the resist stripping solution, the nickel plating as the first metal part 3a is nickel. Etching was performed with an etching solution (Meltex Co., Ltd. Melstrip N-950) so that the width of the circuit was smaller than that of the copper plating as the second metal part 3b, whereby the conductor circuit 3 was formed. As a result, a nickel / copper metal conductor circuit 3 was obtained. Next, in order to form the insulating layer 6 on the metal carrier with the conductor circuit 3, the metal carrier, one prepreg (FR-4, 0.1t) and one copper foil (12 μm) are combined and laminated press Then, heating and pressurization integral molding was performed.
This obtained the laminated board with a metal carrier. Next, after lamination, the end face was processed, and the stainless steel plate 1 was gradually peeled off from the end face. Next, the electroless copper plating 2 was removed by alkali etching to obtain a printed wiring board 7 having a flat conductor circuit 3.
When the surface of the printed wiring board 7 was observed with a metal microscope and measured with a length measuring machine, the conductor circuit width was good within ± 5 μm up to L / S = 50 μm / 50 μm, and the conductor circuit was peeled off. Not observed.

Example 2
1 μm of electroless copper plating 2 was deposited on one surface of a stainless steel plate 1 having a thickness of 0.8 mm. Next, the photoresist 5 was adhered by a laminator, left at room temperature for 5 minutes, and then exposed through a photomask. The test photomask pattern had a line (L) / space (S) = 10 μm / 10 μm, 15 μm / 15 μm, 20 μm / 20 μm, and thereafter 100 μm / 100 μm in increments of 10 μm, and was a positive type.
Photoresist 5 was developed, and the resist was removed at portions where plating thickness was required. Next, 10 μm of the first metal part 3a made of nickel plating was deposited by electrolytic plating, and then 5 μm of the second metal part 3b made of copper plating was deposited. Next, the resist 5 is peeled off, and the nickel plating liquid (Meltex Co., Ltd. Melstrip N-950) is used to make the nickel plating as the first metal part 3a smaller than the copper plating as the second metal part 3b. Etching was performed to form the conductor circuit 3. As a result, a nickel / copper conductor circuit 3 was obtained. Thereafter, a printed wiring board 7 was obtained in the same manner as in Example 1.
When the surface of the printed wiring board 7 was observed with a metal microscope and measured with a length measuring machine, the conductor circuit width was good within ± 2 μm up to L / S = 20 μm / 20 μm, and the conductor circuit was peeled off. Not observed.

Comparative Example 1
1 μm of electroless copper plating 32 was deposited on one surface of a stainless steel plate 31 having a thickness of 0.8 mm by electroless copper plating treatment. Next, 10 μm of the first metal part 33a made of nickel plating was deposited by electrolytic plating, and then 5 μm of the second metal part 33b made of copper plating was deposited. Next, a photoresist 34 was adhered by a laminator, left at room temperature for 5 minutes, and then exposed through a photomask. The test photomask pattern was a line (L) / space (S) = 10 μm / 10 μm, 15 μm / 15 μm, 20 μm / 20 μm, and thereafter 100 μm / 100 μm in increments of 10 μm, and was a negative type. The photoresist 34 was developed, and a resist layer was formed in a portion requiring a plating thickness. Next, the nickel plating 33a as the first metal part 33a and the copper plating as the second metal part 33b were etched with a ferric chloride etchant to form the conductor circuit 33. Thereafter, a printed wiring board 37 was obtained in the same manner as in Example 1.
When the surface of the printed wiring board 37 was observed with a metal microscope and measured with a length measuring machine, the conductor circuit width was good within ± 5 μm up to L / S = 50 μm / 50 μm. The peeling of was confirmed.

Comparative Example 2
1 μm of electroless copper plating 32 was deposited on one surface of a stainless steel plate 31 having a thickness of 0.8 mm. Next, a photoresist 35 was adhered by a laminator, left at room temperature for 5 minutes, and then exposed through a photomask. The test photomax pattern was line (L) / space (S) = 10 μm / 10 μm, 15 μm / 15 μm, 20 μm / 20 μm, and thereafter 100 μm / 100 μm in increments of 10 μm, and was a positive type. The photoresist was developed, and the resist where the plating thickness was required was removed. Then, 10 μm of the first metal part 33a made of nickel plating was deposited by electrolytic plating, and then 5 μm of the second metal part 33b made of copper plating was deposited. Next, the resist 35 was peeled off to form a conductor circuit 33. Thereafter, a printed wiring board 37 was obtained in the same manner as in Example 1.
When the surface of the printed wiring board 37 was observed with a metal microscope and the length was measured with a length measuring machine, the conductor circuit width was good within ± 2 μm up to L / S = 20 μm / 20 μm. The peeling of was confirmed.

The schematic cross-section explanatory drawing of the printed wiring board of this invention. The schematic cross-section explanatory drawing which shows the manufacturing process of the printed wiring board of this invention. Schematic cross-sectional explanatory drawing which shows the manufacturing process of the printed wiring board of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 31: Stainless steel plate 2, 32: Electroless copper plating 3, 33: Conductor circuit 3a, 33a: 1st metal part 3b, 33b: 2nd metal part 4, 5, 34, 35: Photoresist 6, 36: Insulating layer 7: Printed wiring board (product of the present invention)
37: Printed wiring board (conventional product)

Claims (4)

  A printed wiring board having a flat conductor circuit in which a conductor circuit of an outer layer is embedded in an insulating substrate, wherein the conductor circuit is composed of two or more kinds of metal layer portions, and at least an inner layer from the width of the first metal portion on the outer layer side A printed wiring board characterized in that the width of the second metal portion on the side is larger.   In a method for manufacturing a printed wiring board, a metal circuit is deposited on a metal carrier to form a conductor circuit, and then an insulating layer is laminated, and then the metal carrier is peeled off to form an outermost circuit pattern. After forming two or more types of metal layer portions by plating, the width of at least the first metal portion on the outer layer side of the metal layer portion is smaller than the width of the second metal portion on the inner layer side. A method for producing a printed wiring board, comprising etching a metal layer portion to form a conductor circuit.   3. The method of manufacturing a printed wiring board according to claim 2, wherein the etching is performed using an etching solution that dissolves the first metal part but does not dissolve the second metal part.   3. The method of manufacturing a printed wiring board according to claim 2, wherein the etching is performed using an etching solution that dissolves the first metal part but slightly dissolves the second metal part.

Images